The prevention of tooth decay involves regular examinations at the dentist, a six-month check-up generally being recommended. However, this advice is often not heeded because the layman is not aware of his own personal risk of tooth decay and often mistakenly believes that, in his case this risk is minimal.
Accordingly, it would be useful to have a test which could be carried out by the layman himself and which would provide information as to his own personal risk of tooth decay in a simple, quick and inexpensive manner.
The exact causes of tooth decay and the processes involved have not yet been fully explained. What is certain, however, is that tooth decay is linked to the presence of microorganisms and carbohydrates in the oral cavity. The fermentation of carbohydrate-containing food residues which adhere to the teeth results in acidification of the surrounding medium, through formation of the degradation product lactic acid and hence in the dissolution of inorganic salts from the dental hard tissue. Microorganisms are able to migrate into the loosened hard tissue where they attack the organic supporting tissue of the teeth. Tooth decay begins above all in plaque-affected areas.
Investigations by the inventors have shown that the analysis of saliva, particularly in regard to its pH value, can provide information on the risk of tooth decay, as explained in more detail in the following.
Saliva tests and means for removing saliva for analysis purposes have been known for some time. One such process is described in DE 36 32 303 A1. In this process, an elastic, absorbent, inert substance is chewed by the volunteer and then introduced into a centrifuge tube provided with a perforated base. Like many other known processes, however, this process is only suitable for dental clinics and cannot readily be carried out by the layman.
In addition, a mouth swab for oral hygiene is known from the prior art (DE 37 09 497 A1). Arranged at one end of the supporting stick of the mouth swab is a cottonwool bud impregnated with an oral treatment formulation. The treatment formulation is prevented from evaporating by a dry saliva-soluble polymeric coating of the swab so that the oral swab can be stored for long periods without becoming unusable. The coating material consists essentially of acrylic resin and does not contain any carbohydrates. In contrast to the present invention, however, the known oral swab is used to introduce liquid into the mouth and not to remove saliva.
DE 29 41 471 A1 describes a provocation test for tooth decay which uses a liquid test medium. The test medium itself contains not only the carbohydrate but also the pH indicator. The disadvantage of this test lies above all in its complexity. Thus, the tartar taken from the patient has to be incorporated in the test medium which then has to be observed for a change in color after incubation for a fixed period, for example 30 minutes.
U.S. Pat. No. 5,357,989 describes a tooth cleaning material, for example dental floss, which is impregnated or coated with a pH indicator. The subject matter of this document is not a provocation test but merely the measurement of the prevailing pH value.
Another water-based reagent for conducting a test for tooth decay similar to that disclosed in DE 29 41 471 A1 is described in detail in DE 30 48 705 A1. This is also a provocation test because the aqueous reagent solution may also contain sucrose. However, the disadvantage here is again the relatively long waiting time after introduction of the saliva into the test solution which is said to be about 30 minutes. Such a test is inconvenient and complicated for the layman.
EP 0 097 904 A1 uses a paper impregnated with sucrose and a pH indicator. To carry out the test, saliva is applied to this paper. This test also involves incubation for 20 to 30 minutes which is a major disadvantage for application by the layman.
Another test is described in WO 91/14000. The test kit consists of a support with a first porous zone, namely a filter paper impregnated with a color test substance. A second porous zone is impregnated with a color developer. For application, saliva is applied to the first zone after which the support is folded so that the two zones come into contact with one another. Here, too, the disadvantage is the need for incubation at a temperature of about 37.degree. C. over a period of, typically, 15 minutes. The need for a certain minimum temperature alone makes this test impracticable for the layman.
The test according to U.S. Pat. No. 3,746,624 also involves incubation of the sample --in this case for about 48 hours in a solution.
Finally, U.S. Pat. No. 4,976,951 is cited. Here, a sugar-containing chewing gum is chewed for a certain time by the volunteer and is then washed and, finally, incubated in a special liquid for 6 to 24 hours at 35 to 37.degree. C. A test such as this is very complicated for the layman to carry out.